327  WTNT42 KNHC 190255 TCDAT2  Hurricane Grace Discussion Number  23 NWS National Hurricane Center Miami FL       AL072021 1000 PM CDT Wed Aug 18 2021  Grace has become a bit better organized during the past several  hours.  Cuban radar data indicates that the eye and eyewall have  become better defined, and reports from Air Force Reserve and NOAA  Hurricane Hunter aircraft show that the inner core circulation has  become better defined.  There are also occasional attempts at eye  formation in satellite imagery.  However, these changes have not  yet resulted in significant intensification, with the maximum winds  remaining near 70 kt and the central pressure hovering near 988 mb.  One possible restraint on development is a dry slot that is seen wrapping around the central core in both satellite imagery and  Cuban radar data.  The center has jogged a little to the left during the past few  hours, and the initial motion is now 280/16.  The hurricane should  continue to move generally westward to west-northwestward for the  next 24-36 h, followed by a westward to west-southwestward motion  from 36-48 h.  This motion should bring the center over the  Yucatan Peninsula of Mexico during the next 12 h, followed by  passage across the southwestern Gulf of Mexico or the Bay of  Campeche to a second landfall in mainland Mexico between 48-60 h.   After that, the cyclone should continue moving into the mountains  of Mexico until it dissipates.  The new forecast track is nudged a  little south of the previous forecast, and it lies near the various  consensus models.  Except for the aforementioned dry slot, conditions appear  favorable for intensification before landfall on the Yucatan  peninsula.  While not explicitly show in the intensity forecast,  Grace could reach an intensity of 75-80 kt before it reaches  Yucatan.  The cyclone should weaken some as it crosses the  peninsula, then re-intensify over the Gulf of Mexico until it  reaches mainland Mexico.  After final landfall in Mexico, Grace is  expected to quickly weaken and dissipate over the mountains of  Mexico just after 72 h.  The remnants of Grace are likely to emerge  in the Pacific and possibly re-develop there, but the uncertainty  of whether this will be the original center or a new center  precludes forecast points over the Pacific at this time.  A Hurricane Watch and a Tropical Storm Watch have been issued for  portions of mainland Mexico.  Key Messages:  1. Hurricane conditions and a dangerous storm surge are expected in portions of the Hurricane Warning area in the eastern Yucatan Peninsula of Mexico beginning during the next several hours. Preparations to protect life and property should be rushed to completion.  2. There is an increasing risk of hurricane conditions and dangerous storm surge in portions of eastern mainland Mexico beginning late Friday, and a Hurricane Watch has been issued for part of this area.  3. Through the weekend, heavy rainfall across central and northern  portions of the Yucatan Peninsula and Veracruz State should lead to  flash and urban flooding. In addition, the heavy rainfall from Grace  will be capable of producing mudslides in Veracruz.     FORECAST POSITIONS AND MAX WINDS  INIT  19/0300Z 19.8N  85.6W   70 KT  80 MPH  12H  19/1200Z 20.3N  88.1W   70 KT  80 MPH...INLAND  24H  20/0000Z 20.6N  91.4W   60 KT  70 MPH...OVER WATER  36H  20/1200Z 20.7N  94.0W   65 KT  75 MPH  48H  21/0000Z 20.5N  96.1W   75 KT  85 MPH  60H  21/1200Z 20.0N  98.8W   35 KT  40 MPH...INLAND  72H  22/0000Z 19.7N 101.6W   20 KT  25 MPH...POST-TROP/INLAND  96H  23/0000Z...DISSIPATED  $$ Forecaster Beven